1. Field of the Invention
The present invention relates to an air precleaner adapted to be positioned upstream of the conventional air filter on the air intake side of the internal combustion engine for removing the bulk of the intake air contaminates before the air reaches the air filter, thereby prolonging the life of the filter.
2. Description of the Prior Art
The use of air precleaners for the internal combustion engines of vehicles which operate in a dirty environment, such as earth-moving vehicles and agricultural tractors, is well known. The most widely used precleaners are those of the type shown in the Wilson U.S. Pat. No. 3,354,621, issued Nov. 28, 1967. In the Wilson type precleaner, air enters an air intake opening at the upper end of a cylindrical casing past stationary vanes which spin the air and, through centrifugal force, drive dust particles to the periphery of the casing, causing such particles to drop down past a baffle into a dead air compartment at the bottom of the casing. The cleaned air passes downwardly through a central discharge tube leading to a conventional air filter before going to the engine's carburetor. A hose connects the dead air compartment to a venturi tube attached to the engine's exhaust pipe. Suction created at the venturi tube draws collected dirt and dust particles from the dead air compartment and discharges it with the engine exhaust to atmosphere. The venturi tube, connecting hose and attendant couplings add considerably to the cost of the precleaner and complicate installation.
Others have sought to design precleaners which do not rely on engine or exhaust suction to remove collected dirt and dust particles therefrom. For example, Shaw U.S. Pat. No. 2,229,824 discloses a precleaner in the shape of an inverted cone with a tangential upper air intake which induces a downward cyclonic flow to the air stream to discharge dirt and dust into a removable container communicating with a bottom opening of the chamber, while engine suction induces a counterflow of clean air through a central portion of the chamber to the engine. The primary disadvantage of this approach is the required periodic removal and emptying of the container, during which time the powered equipment would be shut down.
Several other devices for cleaning air using a centrifuging action have been suggested, such as those shown in U.S. Pat. Nos. 3,923,481 to Farrow; 3,907,529 to Borsheim; and 3,566,586 to Langness; but the complexity of such devices, with their numerous passageways and/or baffles, will be readily apparent and therefore their cost would be prohibitive.
Accordingly, there is a need for a simplified and effective air precleaner for internal combustion engines which is self-cleaning without reliance on engine or exhaust induced suction to remove collected dirt, and which can be manufactured at low cost.